U.S. patent number 5,628,746 [Application Number 08/347,838] was granted by the patent office on 1997-05-13 for dilatation catheter assembly with cutting element and method of using the same.
This patent grant is currently assigned to Applied Medical Resources Corporation. Invention is credited to Ralph V. Clayman.
United States Patent |
5,628,746 |
Clayman |
May 13, 1997 |
Dilatation catheter assembly with cutting element and method of
using the same
Abstract
A dilatation catheter assembly is set forth which permits
dilatation and incision of tissue whereby trauma and damage to the
tissue due to uncontrolled tearing is reduced or eliminated. The
assembly comprises an elongated tubular body having a distal end
that carries a dilatation bladder and cutting element carried on
the exterior of the bladder and that moves radially in concert with
the exterior of the bladder as the bladder is inflated and
deflated. The bladder is not linearly extensible and is extensible
only to a specified volume and/or the cutting element utilized is a
radio frequency cutting element.
Inventors: |
Clayman; Ralph V. (St. Louis,
MO) |
Assignee: |
Applied Medical Resources
Corporation (Laguna Hills, CA)
|
Family
ID: |
27404570 |
Appl.
No.: |
08/347,838 |
Filed: |
November 30, 1994 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
873712 |
Apr 22, 1992 |
|
|
|
|
522148 |
May 11, 1990 |
|
|
|
|
298477 |
Jan 18, 1989 |
|
|
|
|
Current U.S.
Class: |
606/45; 606/159;
606/192; 606/194 |
Current CPC
Class: |
A61B
18/08 (20130101); A61B 18/1492 (20130101); A61B
2018/00107 (20130101); A61B 2018/00148 (20130101); A61B
2018/0022 (20130101); A61B 2018/00285 (20130101); A61B
2018/00386 (20130101); A61B 2018/00422 (20130101); A61B
2018/1213 (20130101); A61B 2018/1253 (20130101); A61B
2018/144 (20130101) |
Current International
Class: |
A61B
18/04 (20060101); A61B 18/14 (20060101); A61B
18/08 (20060101); A61B 017/39 () |
Field of
Search: |
;606/47,113,159,192,194,45,46,48 ;604/96 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
0336903 |
|
Apr 1988 |
|
EP |
|
0315730 |
|
May 1989 |
|
EP |
|
2427540 |
|
Dec 1979 |
|
FR |
|
2594322 |
|
Aug 1987 |
|
FR |
|
2426781 |
|
Dec 1975 |
|
DE |
|
3402573 |
|
Aug 1985 |
|
DE |
|
3519626 |
|
Dec 1986 |
|
DE |
|
599802 |
|
Nov 1976 |
|
SU |
|
938977 |
|
Jul 1982 |
|
SU |
|
8901800 |
|
Mar 1989 |
|
WO |
|
Other References
Banning G. Lary, MD, et al., "Myocardial Revascularization
Experiments Using the Epicardium" Archives of Surgery vol. 98,
pp.69-72, Jan. 1969. .
Banning G. Lary, MD, "Coronary Artery Resection and Replacement by
a Blood Conduit" Surgery vol. 65, No. 4, pp.584-589, Apr. 1969.
.
Banning G. Lary, MD, "An Epicardial Purse String Suture for Closing
Coronary Arteriotomy" The American Surgeon vol. 33, No. 3,
pp.213-214, Mar. 1967. .
Banning G. Lary, MD et al., "A Method for Creating a Coronary
Myocardial Artery" Surgery vol. 59, No. 6, pp.1061-1064, Jun. 1966.
.
Banning G. Lary, MD, "Method for Increasing the Diameter of Long
Segments of the Coronary Artery" The American Surgeon vol. 32, No.
1, pp.33-35, Jan. 1966. .
Banning G. Lary, MD, "Coronary Artery Incision and Dilation"
Archives of Surgery vol. 115, pp. 1478-1480, Dec. 1980. .
Banning G. Lary, MD et al., "Experimental Vein Angioplasty of th
Circumflex Coronary Artery" Journal of Surgical Research 17,
pp.210-214, 1974. .
Banning G. Lary, MD, "A Method to Create and Correct Stenosis of a
Coronary Artery" Archives of Surgery vol.93, pp.828-830, Nov.
1966..
|
Primary Examiner: Thaler; Michael H.
Attorney, Agent or Firm: Myers; Richard L.
Parent Case Text
This is a continuation of application Ser. No. 07/873,712, filed
Apr. 22, 1992, now abandoned which is a continuation of application
Ser. No. 07/522,148, filed May 11, 1990, now abandoned which is a
continuation-in-part of application Ser. No. 07/298,477, filed Jan.
18, 1989, now abandoned.
Claims
That which is claimed is:
1. A method for dilating a body conduit defined by body tissue, the
method including the steps of:
providing a tubular body having an elongate axis extending between
a distal end and a proximal end, a cutting element comprising not
more than one cylindrical electrosurgical cutting wire being
disposed in proximity to the distal end of the tubular body in a
particular orientation with the axis;
inserting the tubular body with the cutting element into the body
conduit;
advancing the cutting element generally radially outwardly of the
tubular body to contact the body tissue of the conduit, the cutting
element moving generally in a plane which includes the axis of the
tubular body while it is advancing;
activating the cutting element in contact with the tissue to create
in the tissue an incision defined by tissue walls; and
creating in the surrounding tissue a tangential force acting to
separate the tissue walls of the incision thereby expanding the
body cavity.
2. The method recited in claim 1 wherein the tubular body includes
an inflatable member disposed between the tubular body and the
cutting element and during the advancing step the dilatable member
is dilated to move the cutting element radially outwardly into
contact with the surrounding tissue of the body conduit.
3. The method recited in claim 2 wherein during the creating step
the dilatable member is dilated to contact the surrounding tissue
and create in the surrounding tissue the dilation forces.
4. A dilation catheter assembly adapted for insertion into the
urethra of a patient, comprising in combination:
an elongate tubular body having an axis and a distal end carrying a
generally cylindrical radially dilatable member adapted to be
positioned longitudinally in a body conduit and having properties
for dilating generally radially of the tubular body;
means for dilating the dilatable member to exert dilation forces on
the urethra;
cutting means carried by the tubular body exteriorly of the
dilatable member, for creating an incision in the urethra thereby
reducing damage to the urethra from the dilation forces; and
the cutting means being limited to a single cutting element in the
form of a thin cylindrical wire disposed longitudinally of the
tubular body and movable radially in a plane including the axis of
the tubular body to create the incision in the urethra, at least a
portion of said wire being disposed radially outwardly of said
tubular body at all times.
5. The assembly recited in claim 4 wherein the dilatable member is
an inflatable bladder that is adapted to be connected to a source
of inflation fluid.
6. The assembly recited in claim 5 wherein the cutting element is
permanently affixed to the exterior surface of the inflatable
bladder.
7. The assembly recited in claim 5 wherein the cutting element is
adapted to be moved radially outwardly by the inflatable
bladder.
8. The assembly recited in claim 4 wherein the cutting element is
an integral component of the dilatable member.
9. A catheter for dilating a body conduit defined by living tissue,
comprising:
a tubular body having an elongate axis extending between a distal
end and a proximal end;
an elongate cutting element including only a single cylindrical
wire disposed in proximity to the distal end of the tubular body
and having properties for being moved along a plane including the
axis between a retracted position in proximity to the tubular body
and an extended position in proximity to the living tissue, the
cutting element having characteristics for being activated to cut
the living tissue when the cutting element is in the extended
position;
means operable from the proximal end of the tubular body for moving
the cutting element radially of the tubular body from the retracted
position to the extended position in proximity to the living
tissue; and
means for activating the cutting element in the extended position
to create an incision in the living tissue, the activating means
including a generator having electrical power to create a current
density in the tissue proximate to the cutting element in the
extended position, the electrical power being sufficient to cut the
tissue.
10. The catheter recited in claim 9 wherein the particular
direction is generally radially of the tubular member.
11. The catheter recited in claim 9 wherein said single wire is
disposed generally parallel to the axis of the tubular member and
movable generally radially of the tubular member to cut the
tissue.
12. The catheter recited in claim 9 wherein the body conduit is the
urethra and the living tissue defining the urethra is the prostatic
urethra.
13. The catheter recited in claim 9 wherein the body conduit is the
ureter.
Description
TECHNICAL FIELD
The present invention is in the field of surgical devices,
particularly dilatation catheters. Specifically, it concerns a
dilatation catheter whose expandable member carries a cutting
element which concurrently incises the tissue being subjected to
dilatation forces, thereby obtaining a clean and directed incision
and reducing trauma and damage to such tissue from the dilatation
forces.
BACKGROUND OF THE INVENTION
Dilatation catheters are used to dilate body vessels, orifices and
conduits such as an artery narrowed by atherosclerotic plaque
and/or fibromuscular disease or to dilate a constricted or
obstructed ureter or urethra. The prior art devices basically
consist of an elongated catheter having an inflatable extensible
elastomeric (rubber-like) or non-extensible balloon or bladder, at
or near its distal end. A guide wire or other axial support means
is often included to improve the torque control or "steerability"
of the apparatus.
The major advantage of dilatation catheter use over conventional
surgery is that it is less invasive. Nonetheless, the tissue that
is stressed is often also subjected to significant trauma. As the
bladder expands, it exerts pressure on the surrounding tissue,
causing the tissue to compress, deform and expand. The tissue, of
course, has an inherent limit of deformability. When the dilation
pressure causes the tissue to deform beyond that limit, the tissue
tears apart, often to form a jagged wound, with considerable
damage, trauma, pain and bleeding. A principal object of the
present invention is to provide a dilatation catheter that permits
tissue to be stressed, even beyond its limit of deformability,
without experiencing uncontrolled tearing and the undesirable
conditions associated therewith.
U.S. Pat. No. 4,747,405, issued to Leckrone on May 31, 1988, U.S.
Pat. No. 4,669,469, issued Jun. 2, 1987 to Gifford, III, et al.,
and PCT/U.S. 86/02617 application of Leckrone, published Jun. 16,
1988 are each concerned with atherecotomy devices wherein a balloon
is used to position an opening in a casing about an obstruction
such as plaque. The balloon does not carry a cutting element to
incise tissue but does carry means for disintegrating the plaque
which is generally entrapped within a hole in the casing. The
balloon basically positions the hole in the casing up against and
about the plaque. Thus, the balloon is not symmetrically located
within the blood vessel, an outward cutting element is not present
and the blood vessel is not torn by the dilation force.
U.S. Pat. No. 4,799,479, issued Jan. 24, 1989 to Spears, shows use
of a balloon to open up an artery and then utilizes a laser, heated
wire mesh, or the like, to heat up blood trapped between the mesh
and the plaque so that dilation will be maintained and so that a
smooth wall will result.
U.S. Pat. No. 4,273,128, issued Jun. 16, 1981 to Lary, teaches the
use of a balloon with a knife blade, or a series of knife blades,
longitudinally distally removed from the balloon.
Soviet Patent 599802 published in 1976 utilizes a balloon which is
located within a tube. When the balloon is extended this forces a
cutting element through a window in the tube to accomplish
fenestration. Pressure is not exerted on body tissue as the bladder
is within the tube.
German Patent 3,402,573 is concerned with a single lumen
multi-purpose catheter with an extensible elastic balloon with a
cutting facility for treatment of stenosis. This patent utilizes
three balloons of equal size at the distal end of the catheter.
Each elastomeric balloon carries small cutter elements which extend
in the longitudinal direction and which are held in a trough made
of hard rubber or plastic. Prior to use the cutters lie hidden in
longitudinal slots of the relatively thick wall of the one-lumen
catheter. Threads anchor the plate when the balloons are inflated
thereby limiting the degree of penetration of adjacent plaque (and
possibly tissue).
U.S. Pat. No. 4,484,579, issued to Meno, et al, Nov. 27, 1984 is
concerned with a commissurotomy catheter which serves for
separating fused heart valve leaflets. The device includes four
balloons carried by a single catheter structure. In use the device
fits through the valve with two balloons on each side of the valve.
A nylon or similar string is attached between the pairs of balloons
on each side of the valve. The balloons can be alternately expanded
and contracted thereby causing the strings strung between each pair
of balloons to saw or pulsate into fused portions of the heart
valve leaflets and separate them. The actual cutting portion of the
string is not carried on the exterior of the balloons.
U.S. Pat. No. 4,660,560, issued Apr. 28, 1987 to L. A. Klien
discloses an apparatus for relieving obstruction of the urinary
tract caused by an enlarged prostate gland. A balloon is inserted
via a urethral catheter and then is expanded until the prostate has
been forced back from around the urethra. The apparatus of this
patent does not employ a cutter of any sort.
The above-mentioned patents do not make use of a cauterizing (i.e.
an electrosurgical or radio frequency surgical) cutting element.
Nor do the above discussed patents either suggest or show any
advantages for utilizing an inextensible bladder or balloon, i.e.,
a balloon which is not elastomeric (or elastic) and which can be
inflated to only a selected shape and volume and which cannot
extend longitudinally when pressurized. Furthermore, the above
discussed patents are not concerned with a radially symmetrical,
generally cylindrical in shape when expanded, balloon which extends
longitudinally along a body passage and a cutting element which
extends longitudinally along and generally parallel to the balloon,
which balloon creates a substantially uniform tangential tension in
tissue being cut, and which cutting element at the same time
performs the necessary cutting whereby a clean longitudinally
extending incision results and uncontrolled tearing of the tissue
does not occur.
In radio frequency electrosurgical cutting a radio frequency
current is allowed to pass from an active cutting electrode through
a patient's tissue and into a grounding pad or cable. The current
cuts tissue at the active cutting electrode, the cutting rate being
dependant on current density through the tissue in that area. At
low current density heat is generated but no cut is achieved. At
high current density fast cutting occurs.
Current density depends on the voltage applied and can be
controlled utilizing an adjustment present on a conventional
generator utilized for this purpose. The current density also
depends on the series impedance of the overall circuit. Series
impedance is equivalent to the sum total of the resistance to the
current throughout the circuit. It is affected by the material and
the design of the active electrode, by the patient, by the type of
tissue to be cut, and by the condition of contact established
between the patient and the grounding pad as well as by the
location of the pad relative to the cutting site. During surgery,
the generator setting is usually adjusted to compensate for this
variability and to reflect the surgeon's preference. Generators
used in this type of surgery have a wide range of power output to
accommodate a variety of procedures and devices. For example, the
generator can be adjusted to cut tissue, or to cauterize adjacent
already cut or torn tissue, or to do both.
The objective in electrosurgical cutting is to heat the tissues
cells so rapidly that they explode into steam leaving a cavity in
the cell matrix. The heat is meant to be dissipated in the steam
and to not conduct through the tissue to thereby dry out adjacent
cells. When the electrode is moved and fresh tissue is contacted
new cells are exploded and the incision is made. Such
electrosurgical cutting involves the sparking of the current to the
tissue. The current utilized is in the radio frequency range and
operates by the radio frequency current jumping across an air gap
to the tissue. This is known as sparking.
An explanation of electrosurgical cutting theory can be found in
the SSE3B Instruction Manual published by Valleylab of Boulder,
Colo. on Apr. 1, 1979.
An advantage of electrosurgical cutting, particularly if it is
performed utilizing a cutting electrode as disclosed in copending
application Ser. No. 522,254, of Buelna, commonly assigned
herewith, which is hereby incorporated herein in its entirety by
reference, is that overheating of adjacent tissue with accompanying
desiccation and damage is limited or prevented. Thus, what one can
obtain is a clean cut without damage to adjacent tissue. A clean
controlled cut is particularly desirable to assure that tearing
does not occur in a direction away from the desired orientation of
the cut.
The present invention is directed to overcoming one or more of the
problems as set forth above.
Disclosure of Invention
In accordance with an embodiment of the invention a dilatation
catheter assembly comprises in combination: an elongated tubular
body having a distal end carrying a radially dilatable inextensible
longitudinally extending member adapted to be positioned
longitudinally along a body conduit and to dilate in a radially
symmetrical manner and exert pressure on surrounding body tissue to
provide a substantially uniform tangential tension therein; means
for dilating the dilatable member to a constant inextensible volume
and a cutting element carried on the exterior of the dilatable
member that moves radially in concert with the exterior of the
dilatable member and is adapted to incise said tissue, thereby
reducing damage to said tissue from dilation forces.
In accordance with another embodiment of the invention a dilation
catheter assembly comprises an elongated tubular body having a
distal end carrying a radially dilatable member adapted to be
positioned in body conduit and exert pressure on surrounding body
tissue; means for dilating the dilatable member and an
electrosurgical cutting element carried on the exterior of the
dilatable member that moves radially in concert with the exterior
of the dilatable member and that is adapted to incise the tissue,
thereby reducing damage to the tissue from dilation forces.
In use the novel catheter of the invention concurrently exerts
pressure on the tissue thereby placing it under tension and makes a
clean, sharp generally longitudinally extending incision in the
tissue while the tissue is subjected to the dilatation forces
exerted by the dilating member. The incision allows the tissue to
separate along a predetermined path and in a relatively clean,
trauma-free manner as compared to the uncontrolled tearing that
occurs when using prior devices.
Accordingly, another aspect of the invention is a method for
dilating a body conduit, vessel or orifice comprising: inserting
thereinto a dilatation catheter assembly comprising an elongated
tubular body having a distal end carrying a radially dilatable
inextensible member adapted to be positioned in a body conduit and
to dilate in a radially symmetrical manner and exert pressure on
surrounding body tissue to provide a substantially uniform
tangential tension therein and a cutting element carried on the
exterior of the dilatable member; dilating the inextensible
dilatable member to an extent that causes the tissue to be stressed
by the dilatable member; incising the stressed tissue using the
cutting member; radially contracting the dilatable member to cause
the dilatable member and cutting element to disengage the tissue;
and withdrawing the dilation catheter assembly therefrom. The
dilating and incising steps are suitably repeated until the
dilatable member has reached a desired volume prior to the radial
contracting step.
Still another aspect in accordance with the present invention is a
method for dilating a body conduit, vessel or orifice. The method
comprises inserting thereinto a dilation catheter assembly
comprising an elongated tubular body having a distal end carrying a
radially dilatable member adapted to dilate and exert pressure on
surrounding body tissue and an electrosurgical cutting element
carried on the exterior of the dilatable member; dilating the
dilatable member to an extent that causes the tissue to be stressed
by the dilatable member; activating the electrosurgical cutting
element such that the stressed tissue is incised by the cutting
element; discontinuing activation of the electrosurgical cutting
element; radially contracting the dilatable member to cause the
dilatable member and cutting element to disengage the tissue; and
withdrawing the dilation catheter assembly therefrom. The dilating
and incising steps are suitably repeated until the dilatable member
has reached a desired volume prior to the radial contracting
step.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be better understood by reference to the figures
of the drawings wherein like numbers denote like parts throughout
and wherein:
FIG. 1 is a partly cross-sectional, isometric view of one
embodiment of the invention catheter;
FIG. 2 is a cross-sectional view taken along line 2--2 of FIG.
1;
FIG. 3 is a prospective, schematic sectional view of a portion of
another embodiment of the invention catheter positioned within a
body conduit;
FIG. 4 is a sectional, side view of the embodiment of FIG. 3 in its
deflated state;
FIG. 5 is a sectional side view of the embodiment of FIG. 3 in its
inflated state;
FIG. 6 is a cross-sectional view along line 6--6 of FIG. 5;
FIG. 7 is a sectional elevational view of another embodiment of the
invention; and
FIG. 8 is a view similar to FIG. 1 and which includes means for
selectively incising more deeply into a patient's tissue.
BEST MODE FOR CARRYING OUT INVENTION
FIG. 1 depicts a dilatation catheter assembly, generally designated
10, that may be used for dilating a body vessel or conduit, such as
a ureter or urethra, to treat a blockage or other obstruction. The
main elements of catheter assembly 10 are: an adapter 11 that
defines the proximal end 12 of the assembly 10 and a site for
various ports to the assembly 10; a triple lumen catheter body 13
(FIG. 2); an inflatable inextensible balloon or bladder member 15;
and a cutting element 17, very preferably a radio frequency cutting
element activatable by a radio frequency power source. The
electrosurgical cutting element or electrode 17 is in the nature of
a wire which runs along generally parallel to the longitudinally
extending inflatable bladder 15. In use, the bladder 15 is inserted
longitudinally into a body conduit to the position where a surgical
cut is required. The bladder 15 is then inflated (an inextensible
bladder is generally used) to a desired pressure about 1
atmosphere) and allowed to expand to occupy the space in the body
vessel or conduit. Radio frequency current is then passed through
the cutting element 17. This leads to the wire being moved
outwardly and incising adjacent tissue in that direction.
Thereafter, the pressurization and incising steps are suitably
repeated (the pressure drops each time incising occurs) as many
times as is necessary until the bladder 15 is fully inflated. In
this way, the depth of the incision is controlled by the size
chosen for the inextensible bladder 15 and tearing is avoided by
making successive cuts rather than exerting a very large pressure
within the bladder and overstressing the body conduit.
The material used for the wire can be any of the materials
currently used for electrosurgical cutting wires. For example, the
wire can be made of stainless steel or tungsten. In accordance with
the teachings in the previously mentioned copending Buelna patent
application a sheath with a slit in it, the slit facing away from
the bladder 15, surrounds the cutting element 17. As seen in FIG.
2, one of the three lumens serves as an inflation/deflation
passageway 18, a second serves as a drainage/infusion passageway,
and a third carries cutting element 17.
In accordance with the present invention the inflatable balloon or
bladder member 15 is of the inextensible or constant volume
variety, that assumes, when expanded, a specific size and shape.
Thus, the balloon member 15 cannot extend significantly
longitudinally within a body conduit beyond its selected length.
And, further, it can only extend radially to a selected radius,
thus controlling the depth of the incision. Since the balloon
member 15 cannot extend longitudinally, as can elastic or
elastomeric balloons, it must exert the force caused by inflation
of the balloon member 15 radially against an enclosing body conduit
or the like. In contrast, if an elastic or elastomeric balloon is
expanded within a body conduit which has one portion particularly
narrowed and particularly resistant to expansion, the balloon will
simply elongate rather than acting radially outwardly against the
constriction. What is happening is a balance of forces in the
balloon which then expands in the direction of least
resistance.
In accordance with the present invention it is preferred to utilize
a radio frequency cutting element 17 for a number of reasons. One
reason is that a radio frequency cutting element 17 will not
perform any cutting unless and until it is activated by passing a
radio frequency current through it. As a result, accidental cuts
cannot be made away from the area where cutting is desired. And,
with proper control cutting can be very sharply defined leading to
a clean incision without tearing. This radio frequency cutting or
cauterizing technique can, thus, provide significant advantages
over the use of prior art cutters in an apparatus of the nature
disclosed herein.
In accordance with the present invention the balloon member 15
generally extends longitudinally along the body conduit and is
generally symmetrically placed and expandable therein. In this
manner, as the balloon member 15 is expanded, it exerts a
substantially equal tangential tension upon the tissue defining the
body conduit. This results in the incision by the cutting element
17, which would generally proceed parallel to the balloon member
15, being particularly clean. In essence, the incision when made in
this manner proceeds longitudinally along the body cavity and will
generally not go off at an angle as might be the case if the
tangential tension in the body conduit was not substantially
uniform.
In accordance with the most preferred embodiment of the present
invention the cutting element 17 is a radio frequency cutting
element and is parallel to the bladder member 15, the bladder
member 15 extends longitudinally along the body conduit and is of
an inextensible (non-elastic, non-elastomeric) nature and is
symmetrically placed within the body cavity so that on expansion it
exerts a substantially uniform tangential tension upon the tissue
defining the body cavity. This allows all of the advantages of the
present invention to be realized at one and the same time.
The adapter 11 serves as a site for a bladder inflation/deflation
port 19 that is attached to a source of inflation medium (not
shown) for inflating the bladder member 15 or a suction source (not
shown) for deflating the bladder member 15. Port 19 has a valve 20
for regulating the inflation medium or suction, as the case may be.
Port 19 connects into the proximal end of an inflation/deflation
passageway 18 that extends from the port 19 to the bladder member
15. The adapter 11 also serves as a site for the drainage tube
inlet/outlet port 22 and a cutting element port 23. The drainage
port 22 is connected to the proximal end of the lumen that carries
a stylet or guide wire. The drainage port 22 may serve as a site
for removing fluid from the lumen or as a site for infusing fluid
into the lumen. The distal end of the catheter body has a series of
drain holes 24 to facilitate flushing the lumen with fluid or
voiding the bladder member 15. A "banana plug" cutting element
connector 25 is affixed to the end of the cutting element port and
the cutting element 17 extends from the connector through the lumen
of the catheter body 13 and exits therefrom via an aperture 26 and
continues along the exterior of the bladder member 15. The cutting
element 17 can consist of a thin wire which has an external
incising edge that faces outwardly from the bladder member 15.
Alternatively, the cutting element 17 may be a sharp edge, beam,
or, more preferably, a radio frequency cutting or cauterizing
element 17. The element/bladder is/are constructed (e.g., the
element 17 is flexible or expandable) such that the cutting element
17 is carried on the exterior of the bladder member 15 (at least
when the bladder member 15 is inflated) but is not capable of
incising the bladder member 15. If desired, the portion of the
exterior of the bladder member 15 that is exposed to the cutting
element 17 may carry a protective cover (not shown) to further
guard against the bladder member 15 being incised by the cutting
element 17. The cutting element 17 may be carried at a
predetermined spacing from the bladder surface or directly on the
surface. When carried on the surface the cutting element 17 may be
an integral part of the surface or attached to the surface. If
desired the cutting element 17 may be extended/retracted manually
via the connector into/out of the catheter body 13.
For use in urethral dilatation the distal end of the assembly 10
includes an atromatic tip 27. Such structure may not be necessary
or desirable for dilating other conduits/orifices. For urethral
dilation, the assembly 10 may optionally include another lumen and
"Foley" type balloon (not shown) distally of the dilatation bladder
member 15 to anchor the catheter in the bladder neck of the human
body to facilitate correct positioning of the dilatation bladder
member 15 and minimize the possibility of migration and
displacement of the assembly 10.
One or more of the catheter assembly components may be made of
radiopaque materials to facilitate the visualization of the
assembly 10 by the physician during placement of the assembly 10 in
the body vessel/conduit.
A typical surgical procedure in which the catheter assembly 10 is
employed involves the following steps. A cytoscope is first
inserted into the vessel/conduit/orifice to be dilated. Calibration
devices may be inserted through the cytoscope to facilitate
measuring the extent of the vessel/conduit/orifice being dilated.
The dilatation catheter of FIG. 1 is then inserted to the desired
depth in the vessel/conduit. A cytoscope lens may then be inserted
to allow visualization of the catheter and the bladder location.
Fluid may be infused through the drainage tube or cytoscope to
facilitate such visualization. Once in position, the bladder member
15 is inflated. Such inflation causes the cutting element 17 to
move radially outwardly as the bladder surface expands radially
until the cutting element 17 contacts the surrounding tissue. In
accordance with a preferred embodiment of the invention the bladder
member 15 is inextensible as mentioned previously.
As used herein the term "tissue" is intended to include, without
limitation, normal tissue, stomatic tissue, neoplastic tissue
(tumors) or an obstruction such as plaque. Continued radial
expansion of the bladder member 15 positions the cutting element 17
and causes the bladder member 15 to exert pressure on the tissue
thereby subjecting the tissue to a substantially uniform tangential
tension. If the preferred radio frequency cutting element 17 is
utilized a radio frequency current is passed through it. This
combined cutting and dilating action results in the tissue being
expanded without being torn due to a buildup of excess stresses
within the tissue. Instead, the tissue is cut in a clean,
concentrated, generally longitudinal fashion by the cutting element
17 and the dilatation does not uncontrollably tear the tissue and
cause excessive trauma and bleeding. The inflated bladder member 15
provides the additional benefit of acting as a tamponade to reduce
bleeding. The radio frequency cutting element 17 is such that it
incises the surrounding tissue in a manner such as to cause
controlled incising under the combined cutting and dilating
action.
After the vessel/conduit/orifice tissue is incised and dilated and
the blockage/obstruction is relieved, the power through the radio
frequency cutting element 17 is disconnected, if such a cutting
element is used, the bladder member 15 is deflated by connecting
the inflation/deflation port 19 to suction or atmospheric pressure
and opening the inflation/deflation port valve 20 thereto.
Deflation of the bladder member 15 results in a simultaneously
radial retraction of the cutting element 17 out of contact with the
tissue. Once the bladder member 15 is deflated the cutting element
17 may be retracted via the connector 25. If desired, the cutting
element 17 may be retracted prior to complete deflation of the
bladder member 15 and/or the bladder member 15 reinflated and left
in place to act as a tamponade. Often it is desirable to leave the
cutting element 17 in contact with the wound for a time, for
example from about 10 minutes to about 2 hours, until the bleeding
stops or is under control, and then to deflate the bladder member
15 and withdraw the catheter. Alternatively, the catheter can
simply be withdrawn from the vessel/conduit altogether. The
particular details of operation are determined by the surgeon
depending upon the particular procedure being carried out and the
particular person being operated upon.
FIGS. 3-6 depict another dilatation catheter assembly of the
invention, generally designated 29, in use. Only the distal end of
the assembly 29 is shown. Adapter(s), inflation/deflation ports are
not shown for convenience. The distal end is defined by a closed
end catheter tube 32 which carries an inflatable, preferably
inextensible, bladder member 33 on its exterior. The lumen 34 of
the tube 32 is connected to the source of inflation fluid/suction,
as the case may be. The tube 32 has a radial aperture 35 that opens
into the lumen 36 of the bladder member 33. A pair of expandable
ring-shaped members 37,38 extend around the exterior of the bladder
member 33 near the distal and proximal ends thereof. One or more
cutting elements 39 are affixed between the rings so that they
extend longitudinally and outwardly therefrom.
FIGS. 3 (in solid line) and 4 show the assembly 29 in its deflated
state positioned within a vessel 42 partially obstructed by an
obstruction 43. In order to inflate the bladder member 33,
pressurized fluid is passed through catheter tube lumen 34 and
aperture 35 into the bladder lumen. Inflation of the bladder member
33 in turn causes the ring members 37,38 to expand and move the
cutting element(s) 39 radially outward. FIGS. 3 (phantom line), 5,
and 6 show the bladder member 33 in an inflated state with the
cutting element 39 incising the obstruction.
FIG. 7 shows yet another dilatation catheter assembly, generally
designated 46, of the invention. The assembly 46 is shown in its
deflated state. This assembly 46 is similar in structure to
assembly 29 except that the assembly 46 is housed within a sheath
or introducer 47 and a cauterizing element 48 is connected to the
cutting element 39. The sheath permits the assembly 46 to be
introduced into the vessel in an unexposed manner, ejected from the
end thereof for use, and retracted back into the sheath 47 after
use. The ejection and retraction may be achieved by relative
longitudinal movement of the sheath 47, assembly 46, or both. The
cutting element 39 can be a radio frequency cutting element and
cauterization will result along with the cutting. Also, following
cutting a coagulation producing radio frequency signal can be
passed through cutting element 39.
FIG. 8 illustrates an embodiment of the invention wherein the
cutting element 17 can be advanced beyond the supporting surface of
the bladder 15. In the embodiment of FIG. 8 the cutting element 17
has an actuator 55 attached to it in the area of the adapter 11,
the actuator extending through the adapter 11. After incision has
been completed using the bladder 15, that is, after the bladder 15
has been fully extended and the cutting element 17 has cut as
deeply as it will when supported by the bladder 15, the surgeon can
electively advance the actuator 55, thereby advancing the cutting
element 17 and causing it to bow outwardly and away from the
bladder 15 and, when a radio frequency current is passed through
it, incise further into the tissue a desired distance.
Industrial Applicability
The present invention provides an apparatus and method for
controlled surgical dilation and incision within body conduits,
vessels and orifices which virtually eliminates tearing and trauma
caused by dilation beyond the strength of the tissue forming the
body conduit, vessel or orifice being dilated.
While the invention has been described in connection with specific
embodiments thereof, it will be understood that it is capable of
further modification, and this application is intended to cover any
variations, uses, or adaptations of the invention following, in
general, the principles of the invention and including such
departures from the present disclosure as come within known or
customary practice in the art to which the invention pertains and
as may be applied to the essential features hereinbefore set forth,
and as fall within the scope of the invention and the limits of the
appended claims.
* * * * *